Frame and operating mechanism for circuit breakers



March 16, 1965 3,174,021

FRAME AND OPERATING MECHANISM FOR CIRCUIT BREAKERS E. C GOODWIN, JR

6 Sheets-Sheet 1 Filed July 1'7, 1962 Q1 amvm/k rl game/:44 .Q. 5000140444, JP. m 5/2 Qua/a March 16, 1965 E. c. eooowm, JR 3,174,021

FRAME AND OPERATING MECHANISM FOR CIRCUIT BREAKERS Filed July 17, 1962 6 Sheets-Sheet 2 a c mm/n/Eorl 8014 0144 .8. fmdmm, 3/1.

March 16, 1965 E. c. GOODWIN, JR 3,174,021

FRAME AND OPERATING MECHANISM FOR CIRCUIT BREAKERS 6 Sheets-Sheet 5 Filed July 1'7 1962 March 16, 1965 E. c. soonwm, JR 3,174,021

FRAME AND OPERATING MECHANISM FOR CIRCUIT BREAKERS 6 Sheets-Sheet 4 Filed July 17, 1962 vKf J/wmkorl 5 14mm .6. gppolw/iwll 3W March 16, 1965 E. c. GOODWIN, JR

FRAME AND CPEIRATING MECHANISM FOR CIRCUIT BREAKERS 6 Sheets-Sheet 5 Filed July 1'7, 1962 5/95 FA/l. FORCE A 5 c M M Mm w w M A Til. I. if} W W W M r r: .L w J r\ MAN Q g i g a W Pa 6 f M MP f A: f z /W MP a WW m m, Z 2. 1g 6 a a J m 7 m aw JZ 1V1- a II. 9 a 170/ .M f .1 5 I. a v z I I f i March 16, 1965 E. C. GOODWIN, JR 3,174,021

FRAME AND OPERATING MECHANISM FOR CIRCUIT BREAKERS Filed July 17, 1962 6 Sheets-Sheet 6 F5504 74/V7' [KEPT/64L FORCE J L GAMMA 20mm ,9. g vel/10AM, Jr}.

United States Patent 3,l?4,ll21 FRAME AND GPERATHNG MEQHANlSli i Filth (ZERCUIT BREAKERS Edwin C. Goodwin, in, Canton, Mass, assign-or to Ailis= Chalmers Manufacturing Company, Milwaukee, Wis. Filed duly 17, 1962, Ser. No. Zltlfil 18 Claims. (Ql. Edd-153) This invention relates to a circuit breaker structure and more particularly to a new and improved frame and circuit breaker operating mechanism for opening and closing a pair of arcing contacts.

In the low voltage circuit breaker structures of the conventional type with links, cranks and other mechanism placed within a relatively heavy box type frame, it has been necessary to rigidly attach this frame to cooperating structure which supports the primary electrical contacts. The heavy box type frame and the necessary welding joints, multiple bolting, etc. of the box to the cooperating switchgear structure rendered this mechanism highly inaccessible for servicing, repairing or maintenance of the component parts thereof. Further the box type frame structure resulted in a frame geometrical configuration which incorporated unnecessary metal thickness and weight.

In accordance with the invention disclosed a new and improved circuit breaker structure is provided for use with, but not limited to, low voltage air circuit breakers of the 600 volt class. This new structure is an improvement over the prior art in that it places the operating mechanisms (the components) outside a single center plate type support frame where they are readily accessible for inspection, adjustment, cleaning and lubricating. This accessibility feature is of prime importance in the maintenance of protective equipment of this type. Further, it permits the use of a minimum number of parts of minimum size and complexity. This is accomplished by a structural design which eifectively relates the stresses in posed by the breaker operation to the placement of frame components. Component sections and fastening means are reduced to the ultimate minimum.

The new and improved placement of the circuit breaker components provides adequate protection for all of the parts involved as well as protecting personnel against accidental involvement therewith. Still further, the use of a minimal size structural component allows added space adjacent to the breaker structure for the placement of control components such as static overcurrent trip devices, relays, auxiliary switches and so forth which the present day breaker structures employ. The single center plate mechanism support of the disclosed structure increases the space adjacent the primary conducting means, thus facilitating inspection and maintenance as well as radiational cooling. The center plate mechanism support is not susceptible to transient strain during operation, which condition could cause displacement between cooperating parts of the circuit breaker operating mechanism.

In accordance with the invention claimed a circuit breakor structure is provided comprising in combination a frame having a leg member and a cross member extending laterally from the leg member. The leg member may be considered the single center plate mechanism support disclosed above. At least one relatively stationary contact is mounted on the cross member. A shaft is set forth as being rotatably mounted on the leg member and is arranged to extend laterally therefrom. At least one rela tively movable contact is mounted on the shaft for cooperation with the stationary contact. Means are mounted on the leg member for actuating the shaft to open and close the contacts. The forces resulting from the opening and closing of the contacts are set forth as being coplanar.

It is, therefore, one object of this invention to provide dim-fi m Patented Mar. 16, 1965 a new and improved contact controlling mechanism for a circuit breaker structure.

Another object of this invention is to provide a new and improved frame structure for a circuit breaker mechanism.

A further object of this invention is to provide a new and improved frame and contact controlling mechanism wherein the forces resulting from opening and closing of the contacts are all coplanar.

A still further object of this invention is to provide a new and improved frame and contact controlling mechanism wherein the sum of the stresses from the opening and closing the contacts is zero.

A still further object of this invention is to provide a new and improved low voltage air circuit breaker structure wherein the forces resulting from the opening and closing of contacts employing rotary motion converted into linear motion are arranged coplanar with one portion of the frame structure.

A still further object of this invention is to provide a new and improved structural design which efiectively relates the stresses imposed by circuit breaker operation to the placement of frame components.

A still further object of this invention is to provide a ne v and improved circuit breaker frame structure employing a single plate for supporting all of the contact actuating mechanisms.

A still further object of this invention is to provide a new and improved frame and circuit breaker operating mechanism employing a minimum number of parts of minimum size and complexity which are simple to corn struct and dependable and easily maintained. I

Gbjects and advantages other than those set forth will be apparent from the following description when read in connection with the accompanying drawings in which:

FIG. 1 is a side elevation with parts broken away illustrating a circuit breaker structure utilizing a transmission mechanism employing the present invention and showing the contact closing and opening springs in their unbiased and biased positions, respectively,

FIG. 2 is a side elevation with parts broken away similar to that illustrated in FIG. 1 wherein the closing springs are shown charged and the opening spring discharged;

FIG. 3 is an isometric view partly in section of the frame structure shown in FIGS. 1 and 2;

FIG. 4 is a cross sectional view of the structure shown in FIG. 1 taken in the direction of the arrows IV-IV;

FIG. 5 is a top view of the frame structure shown in FIG. 3 illustrating the placement of the relatively movable and stationary arcing contacts;

MG. 6 is a front view of the circuitbreaker frame structure shown in FIG. 3;

PEG. 7 is a diagram illustrating the components of the coplanar forces superimposed on the top view shown in FIG. 5 with the components individually identified;

FlG. 8 is an isometric view of a simplified version of the frame structure shown in FIG. 3 illustrating another view of the coplanar forces with the components individ ually identified;

FiG. 9 is a diagram illustrating the coplanar force components superimposed on a side elevational view similar to that shown in FIGS. 1 and 2;

FIG. 10 is a diagram showing the resultant of the forces illustrated in FIG. 9; and

PEG. 11 is a diagram illustrating the coplanar force components as superimposed on a view similar to that shown in FIG. 4.

Referring more particularly to the drawings by characters of reference FIGS. 1 through 6 illustrate a circuit breaker in employing a single center plate mechanism support frame 12. Frame 12, as more clearly shown in FIG. 3, comprises a T-shaped construction employing a single frame leg member 13 attached to a back plate or cross member 14which extends laterally from the leg member 13. The leg member 13 may be attached in any suitable way to the cross member 14 such as by welding, bolting and so forth or it may be formed with cross member 14 out of one piece of material. Although the frame is formed of a metal any suitable plastic material may be used.

The leg and cross members 13 and 14 of the T-shaped frame are mutually braced by side rails 15 and 16 and an apron 17. Because the T-shaped frame provides a means for symmetrical, balanced placement of the circuit breaker operating mechanism around the leg member 13, the rails 15, 16 are subjected only to the tension stress of the toggle 61 (FIG. 1) thereby requiring only a minimum of material Weight and strength.

Leg member 13 is formed of two flanged pieces 18 and 18 arranged in juxtaposition with their fiat surfaces 19, 19' adjacent each other and their flanged reinforcing edges 20, 20' extending laterally from the flat surfaces outwardly of each other as shown in FIG. 3. At the free end of leg member 13 reinforcement blocks of metal 21 are attached to surfaces 19, 19' and are so formed to provide a cavity 22 extending through the flange surfaces at the free end of the leg member (as shown) for receiving parts of the circuit breaker operating mechanism 28, hereinafter described.

As noted from the drawings and particularly FIG. 3 thereof the cross member 14 is provided with apertures 23, 24 and a flange edge 25 which extends outwardly of the flat surfaces 26 of cross member 14 toward the leg member 13. A piece of insulating material 27 is mounted on cross member 14 between flange edge 25 with cleats 30 and 31 extending through apertures 23 and 24, respectively, for supporting the current conducting elements on bus bars 32 and 33 of the energizing circuit.

Circuit breaker 10 utilizes a transmission mechanism 35 for actuating an arcing contact controlling mechanism 36. The transmission mechanism 35 comprises a pin 37 having rotatably mounted thereon a cam 38. Cam 38 is rotated by a manually rotatable handle 39. Pin 37 extends through cavity 22 of leg member 13 and is rotatably mounted on metal blocks 21. Cam surface 38 is arranged to extend within cavity 22 and upon rotation thereof drives a cam roller 40. Cam roller 40 is mounted within cavity 22 on a pin 41. 'Pin 41 extends through cavity 22 with the ends thereof loosely mounted in kidney-shaped slots 42, one :of which is formed in each of the surfaces of the metal blocks 21. 'A pair of links 44 (one of which is shown in FIGS. 1 and 2) are pivotally mounted on pin 41 one at each end of pin 41 between slots 42 and the ends of the pin on each side of leg member 13. The other ends of links 44 are pivotally connected one to each end of a pin 45. Pin 45 is arranged to extend within aligned slots 46 formed in the adjacent surfaces 19, 19 of leg member 13. .A pair of resilient rollers 47 are mounted on pin 45 one at each end thereof and come to rest at the bottom of slot 46 against the top of metal blocks 21 mounted on the outside of surfaces 13, 19'. To the ends of pin 45 is fixedly attached a pair of tension springs one arranged on each side of leg member 13. The other ends of springs 50 are fixedly attached to leg member 13 at point 51. Thus, upon counterclockwise rotation of handle 39, earn 38 forces roller 40 upwardly along the kidney-shaped slot 42 causing the upward movement of pin 45 and link 44 causing a tensioning or charging of spring 50. A spring biased prop latch 49 bears against roller 40 mounted on pin 41 and holds springs 50 in this charged position.

A pair of closing cams 52 having cam surfaces 52 are pivotally mounted between the ends thereof one at each end of a pin 53. Pin 53 is mounted to extend through and be supported by metal blocks 21 on surfaces 19, 19 of leg member 13. One end of each of 4 the closing cams 52 is pivotally mounted at different ends of pin 41 outside of the surfaces of block 21. Thus, as pin 41 is pushed upwardly in kidney slots 42, cams 52 are pivoted clockwise about pin 53.

As shown in FIGS. 1 through 6 the arcing contact mechanism 55 includes three pair of cooperating contacts 55a, 55b, 55c and 56a, 56b, 560. The relatively stationary contacts 56a, 56b and 56c are mounted on the cross member 14 with the stationary contact member 56b mounted on cross member 14 substantially within the plane of leg member 13. Contact members 56a and 560 are mounted one on each side of contact 56b. The relatively movable contacts 55a, 55b and 55c are actuated by shaft 72 through toggles 61 to cooperate with the stationary contacts with contact 55b being mounted substantially within the plane of leg member 13 and contacts 55a and ESL being mounted one on each side symmetrically of leg member 13. In FIG. 1 the cont acts are shown in contact closed position before the stored energy springs 56 are charged by counterclockwise rotation of handle 39. FIG. 2 shows the contacts in contact open position after the stored energy springs 50 have been charged.

The contact controlling mechanism comprises cooperating overcenter toggle 6t and an oifcenter toggle 61. Each toggle arm comprises a pair of spaced parallelly arranged arm members as shown in FIG. 4, however, for purposes of simplification each toggle arm is referred to as a single member. Toggle comprises a pair of toggle arms 62 and 63 interconnected at adjacent ends by a toggle roll 64. Toggle roll 64 is acted upon by closing cam 52. The free end of toggle arm 62 is pivotally mounted in a kidney-shaped slot 65 in leg member 13. Bell crank 66 is pivotally mounted at 67 on leg member 13 and is biased in a counterclockwise direction by a spring 68.

The free end of toggle arm 63 is pivotally connected to the knee of toggle 61. Toggle 61 comprises a pair of toggle arms 70 and 71. Toggle arm 70 is fixedly mounted on a shaft 72. Shaft 72 is rotatably attached to the ends of apron 17. Toggle arm 71 is pivotally attached to the movable arcing contact 55. Asshown in FIGS. 1 and 2 the center movable contact structure 55b of the three phase system is shown wherein the knee of toggle 61 is directly connected to the end of toggle arm 63. The movable contact structures 55a and 550 of the other two phases each employ a toggle 61 which is directly connected through toggle arm 7% to shaft 72 and are actuated thereby. Only the center phase of the three phase system has the knee of its toggle 61 connected to the end of toggle arm 63 of toggle 60.

A pair of contact opening tension springs 75 are connected one at each end to flanges 76 fixed to shaft 72. The other end of springs 75 are connected to the circuit breaker frame structure at 77.

With the circuit breaker in open position as shown in FIG. 2, the cooperating toggles 6t) and 61 are in their collapsed positions. This collapsed condition is maintainable when the stored energy closing springs 59 are charged since in this condition the closing cam 52 is down and out of the way and cam roller 64 at the knee of toggle 6t) can collapse to the left counterclockwise as the breaker contacts open. This function is dependent on releasably restrained connection of toggle arm 62 to the slot 65 and bell crank 66 through pin 78.

With the toggles 6t) and 61 collapsed as shown in FIG. 2 and springs 50 charged, roller 64 on the knee of toggle 60 moves along the cam surface of closing cam 52. Spring biased prop latch 49 bears against roller 40 and holds springs 56 in their charged condition. With the release of latch 49' by downward pressure as shown in FIG. 2 closing cam 52 is rotated counterclockwise driving the roller 64 and the knee of toggle 69 to its overcenter position against a resiliently cushioned stop 31). This motion effects movement of toggle 61to close the arcing contacts.

Closure of the arcing contacts results in charging of the contact opening springs '75. A component of the opening reaction of springs 75 results in a clockwise rotational bias of bell crank 6%. This rotation is controlled by rotary latch 33. Latch 83 comprises a notched pin 84. Clockwise rotation of bell crank 65 causes an edge 85 thereof to be biased against latch 83. A small rotation of latch 33 by the inward movement of release rod 35 releases bell crank 66 and the force of springs 75 revolves bell crank clockwise. The knee of toggle ea rides vertically downward along the face of the stop 2%. Pin 78 at the free end of toggle arm 52 rides downwardly in slot 65 in frame member 13. This downward vertical motion of toggle 6G causes collapse of toggle 61 and opening of the arcing contacts. This action may occur even though closing cam 52 is in the up or spring discharged position shown in EEG. l.

Rotation or cam 52 away from stop 87 to the charged position of springs 59 as previously described will permit toggle 66 to collapse to the left under the toggle collapsing influence of the toggle breaking spring 83. toggle linkage so is again in position for a reclosure of the contacts.

A description of the circuit breaker operation is as follows: with the circuit breaker in the open position as shown in FIG. 2 with the arcing contacts 55 and 56 open the double toggles 6i and 61 formed by toggle arms 62, 63 and 7b, '71, respectively, re collapsed. This collapsed condition can be maintained only when the stored energy closing springs 50 are charged by counterclockwise rotation of a handle 39. This rotation of handle 39 causes the clockwise movement of closing cam 52 to a position Where the knee of toggle (all can collapse to the position Shown in FIG. 2.

To close the arcing contacts of the circuit breaker, toggle 6% must be moved to its overcenter position. This is accomplished by moving downwardly trip latch which releases pin 41 for movement downwardly in slot 42 and under the action of the bias of springs 53 causes closing cam 52 to rotate counterclockwise to move the toggles 6t and 61 thereby closing the arcing contacts and 5e. This position is shown in FIG. 1.

A component of a previous opening reaction provided by accelerating contact opening springs 75 results in a clockwise rotation component of hell crank 65. This rotation is controlled by latch 33.

Opening of the arcing contacts occurs upon a small rotation of shat This occurs upon the inward movement of red as as shown in F268. 1 and 2. The previously referred to force component acting on latch 83 by bell crank es revolves bell crank as and causes toggle 6% to ride vertically downward along cam face 82. of toggle breaking spring El. This vertical motion of toggle 6% causes toggle 63 to collapse and the circuit breaker to open even though cam 52 is in the up or spring discharged position shown in FIG. 1. Rotation of cam 52 to the charged position by handle 39 previously described allows toggle 69 to collapse to the left under the influence of toggle breaking spring 81 which bears against the toggle knee. The linkage comprising toggles and 61 are again in a position for a reclosure operation.

FIGS. 7 through 11 illustrate the force components of the operating mechanism. These force components in some of the figures are superimposed upon the circuit breaker frame structure to clearly illustrate the effective and advantageous combining of the forces coplanarly. In these figures the individual force components are shown as a beam or column in equilibrium. No stresses imposed by the support of the breaker in the cubicle are a part of this analysis since they are of a decidedly secondmy nature.

Since the purpose of this analysis is to describe the type and direction of the stresses imposed by the breaker in operation, all views and diagrams are shown with the breaker in the closed position. The abbreviation lviMR stands for magneto-mechanical reaction and is defined as Thus, the a the algebraic total of the magnetic forces and the mechanical springs, accelerating springs, etc. The reference characters identify the same part in each of the figures.

As noted in FIG. 7, shaft 72 is supported by the side rails 15 and 16. Three concentrated loads are shown with one on the center line through leg member 13 and two symmetrically located about the center line of leg member 13 along toggle 61 in phases A and C. Toggle arms 7:: and 71 of toggle or are loaded in compression.

While the primary copper is designated as a single element in each phase, for purposes of this analysis the primary copper comprises the cooperating members of the arcing contacts, namely the main and arcing contacts of the movable contacts 55, the stationary contacts 56, and the primary bus conductors 32 and 33.

The cross member 114 which serves as the base of the T-shaped frame structure is supported upright at both ends by rails 15 and 16. Three concentrated loads are applied to the primary copper as shown, one on the center base of leg member -13 and two symmetrically located about the center line. These loads are the MMR reac' tions per phase.

The stress in side rails 15 and 16 is essentially puretension since it is located in the plane of toggle arms '10 and 71 of toggle 51, note FIG. 9. The effective tension stresses in the side rails is not substantially different as the breaker closes. When the circuit breaker is in normal operation, the MMR loads imposed at phases A, B and C are accepted equally by the side rails 15 and 16. The extreme condition of the side rail loading is encountered when the maximum current is reached in either one of the outer phases A or C. Under this condition, the side rails 15 and 16 adjacent to the maximum current phase receives a higher tension stress.

Since all of the stresses imposed by the MMR loads (except vertical toggle component load R FIGS. 9 and 10) are completely contained within a parallelogram formed by shaft 72, side rails 15 and 16 and cross member la, the mechanism frame is isolated fromany external stresses and thus its reactions need not exceed those required by the stresses imposed by the operating mechanism. This condition is illustrated byFIG. 8.

in FIG. 9 the force diagram illustrates the vertical toggle arms 62 and 63 of toggle 6t} loaded in compres sion. The trip latch 65 is shown loaded in compression and is releasably restrained by pin 84 of latch 33. Pin 84 is supported in the middle by leg member 13 and two concentrated loads are symmetrically located about its middle support or hearing.

Since the leg member 33 comprising the mechanism frame is fastened to cross member 14 at point B and through side rails 15, re and apron 17 at point D it becomes in essence a beam supported at both ends with a single concentrated load R unsymmetrically placed. This is more clearly noted from HG. 10. The value R is determined by the elf-center setting of toggle arms and 71 and is limited to a very nominal value with the circuit breaker closed in order to keep the required tripping force at a minimum. It is noted that during the closing cycle the resultant force R reaches a somewhat higher transient value due to the changing toggle arm angles. Thus, the fastenings which support the mech anism frame are of minimum size and quantity as they are required to resist only the nominal shear stresses imposed by load R.

PEG. 11 illustrates diagrammatically the forces on the vertically arranged leg member 13 of the T-shaped frame. The toggle pin 88 interconnecting toggle arms 70 and 71 of toggle 61 and the end of toggle arm 63 of toggle 61 is supported at both ends with two symmetrically placed concentrated loads. The toggle pin 8? connecting together toggle arms 52 and 63 of toggle 6t) and supporting toggle roll 64 is supported at both ends having two symmetrically placed concentrated lo'ads. Toggle pin 78 connecting toggle arm 62 to bell crank 66 is also supported '7 at both ends and has two symmetrically placed concentrated loads.

The external loading applied to the mechanism frame by the vertical toggle component load R is transmitted to the frame through symmetrically disposed vertical toggle arms 62 and 63, toggle pins 38, 89 and 78 and trip rod 84. Since the frame is not subjected to torque stresses in the lateral plane due to unsymmetrically applied loads, the lateral st-iifness of the frame can be held to the minimum required to support the operating mechanism.

Thus, the resultant forces for opening and closing of the contacts and the charging of springs 50 and 75 are substantially coplanar or parallel with the leg frame member 13 of the circuit breaker structure. Further, the sum of the stresses resulting from opening and closing of the contacts is substantially zero.

Although but one embodiment of the present invention has been illustrated and described it will be apparent to those skilled in the art that various changes and modifications may be made therein Without departing from the spirit of the invention or from the scope of the appended claims.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to be performed, I declare that What I claim is:

1. A circuit breaker structure comprising in combination a frame having a single leg member and a cross member extending laterally from said leg member, a relatively stationary contact mounted On said cross member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a relatively movable contact mounted on said shaft for cooperation with said stationary contact, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said con tacts being substantially coplanar with each other.

2. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, a relatively stationary contact mounted on said cross member substantially within the plane of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a relatively movable contact mounted on said shaft for cooperation with said stationary contact, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of sand contacts being substantially coplanar with each other.

3. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, a relatively stationary contact mounted on said cross member substantially within the plane of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three movable contacts mounted on said shaft for cooperation with said stationary contact, :and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being substantially coplanar with said leg member.

4. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extendinglaterally from said leg member, a pair of relatively stationary contacts spacedlyv mounted on said cross member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a pair of movable contacts mounted on said shaft one cooperating with each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the resultant of the forces for opening and closing said contact being substantially coplanar with said leg member.

5. A circuit breaker structure comprising in combina tion a frame having a leg member and a cross 'member extending laterally from said leg member, a pair of relatively stationary contacts spacedly mounted on said cross member one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a pair of movable contacts mounted on said shaft one cooperating with each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the resultant forces for opening and closing said contacts being substantially coplanar with said leg member.

6. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, a pair of rela tively stationary contacts spacedly mounted on said cross member one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a pair of movable contacts mounted on said shaft one cooperating with each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the resultant forces for opening and closing said contacts being substantially parallel to said leg member.

7. A circuit breaker structure comprising in combination a T-shaped frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially Within the plane of said leg member and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three movable contacts mounted on said shaft one cooperating With each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the

esultant forces for opening and closing said contacts being substantially parallel with said leg member.

8. A circuit breaker structure comprising in combination a T-shaped frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially within the plane of said leg member and the other two of. said stationary contacts being nounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three movable contacts mounted on said shaft one cooperating with each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being coplanar with each other.

9. A circuit breaker structure comprising in combination a T-shaped frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary cont-acts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially within the plane of said leg mem ber and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three movable contacts mounted on said shaft one cooperating With each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being coplanar With said leg member.

10. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, a relatively stationary contact mounted on said cross member, a shaft rotatably mounted on said leg member and extending laterally therefrom, a relatively movable contact mounted on said shaft for cooperating with said stationary contact, spring means mounted on said leg member for closing said contacts upon bias thereof, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being substantially coplanar with each other.

11. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially Within the plane of said leg member and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rot-atably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contacts, spring means mounted on said leg member for closing said contacts upon bias thereof, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being substantially coplanar with each other.

12. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially Within the plane of said leg member, and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contact, spring means mounted on said leg member for closing said contacts upon bias thereof, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts being coplanar with said leg member.

13. A circuit breaker structure comprising in combination a T-shaped frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially within the plane of said leg memher, and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contacts, spring means mounted on said leg member for closing said contacts upon bias thereof, means for converting the motion of said shaft into linear motion for biasing said closing means, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from opening and closing of said contacts and charging of the two spring means being substantially coplanar.

14. A circuit breaker structure comprising in combination a frame having a leg member and a cross member "id extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member one of said stationary contacts being mounted substantially Within the plane of said leg member, and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contacts, spring means mounted on said leg member for closing said contacts upon bias thereof, means comprising an overcenter toggle for converting the motion of said shaft into linear motion for biasing said closing means, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the forces resulting from said overcenter toggle and the two spring means being substantially coplanar.

15. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially within the plane of said leg member, and the other two of said stationary contacts being mounted one on each side of said leg members, a shaft rotatably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contacts, spring means mounted on said leg member for closing said contacts upon bias thereof, means for converting the motion of said shaft into linear motion for biasing said closing means, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, means mounted on said leg member for actuating said shaft to open and close said contacts, and means for triggering said opening spring means to open said arcing contacts, the forces resulting from biasing said closing means and for opening and closing of said contacts being substantially coplanar.

16. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three relatively movable contacts mounted on said shaft for cooperating with said stationary contact, spring means mounted on said leg member for closing said contacts upon bias thereof, means for converting the motion of said shaft into linear motion for biasing said closing means, spring means mounted on said leg member for opening said contacts upon bias thereof, said closing spring means being connected to said opening spring means for biasing said opening spring means during closing of said contacts, means mounted on said leg member for actuating said shaft to open and close said contacts, and means for triggering said opening spring means to open said arcing contacts, the forces resulting from biasing said closing means and for opening and closing of said contacts being substantially coplanar, said forces resulting from opening and closing of said contacts being lateral to said closing means biasing forces.

17. A circuit breaker structure comprising in combination a frame having a leg member and a cross member extending laterally from said leg member, a relatively stationary contact mounted on said cross member, a shaft rotatably mouned on said leg member and extending laterally therefrom, a relatively movable contact mounted on said shaft for cooperation with said stationary contact, and means mounted on said leg member for actuating said shaft to open and close said contacts, the sum of the stresses resulting from opening and closing of said contacts being substantially zero.

18. A circuit breaker structure comprising in combination a T-shaped frame having a leg member and a cross member extending laterally from said leg member, three relatively stationary contacts spacedly mounted on said cross member, one of said stationary contacts being mounted substantially Within the plane of said leg member and the other two of said stationary contacts being mounted one on each side of said leg member, a shaft rotatably mounted on said leg member and extending laterally therefrom, three movable contacts mounted on 12 said shaft one cooperating with each of said stationary contacts, and means mounted on said leg member for actuating said shaft to open and close said contacts, the resultant stresses for opening and closing of said contacts being substantially zero.

References Cited by the Examiner UNITED STATES PATENTS 2,338,715 1/44 Graves 200-446 X BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner. 

1. A CIRCUIT BREAKER STRUCTUE COMPRISING IN COMBINATION FRAME HAVING A SINGLE LEG MEMBER AND A CROSS MEMBER EXTENDING LATERALLY FROM SAID LEG MEMBER, A RELATIVELY STATIONARY CONTACT MOUNTED ON SAID CROSS MEMBER, A SHAFT ROTATABLY MOUNTED ON SAID LEG MEMBER AND EXTENDING LATERALLY THEREFROM, A RELATIVELY MOVABLE CONTACT MOUNTED ON SAID SHAFT FOR COOPERATION WITH SAID STATIONARY CONTACT, AND MEANS MOUNTED ON SAID LEG MEMBER FOR ACTUATING SAID SHAFT TO OPEN AND CLOSE SAID CONTACTS, THE FORCES RESULTING FROM OPENING AND CLOSING OF SAID CONTACTS BEING SUBSTANTIALLY COPLANAR WITH EACH OTHER. 